David A Feinberg^1,2,3, Salvatore Torrisi^1,2, Alexander JS Beckett^1,2, Rüdiger Stirnberg⁴, Tony Stöcker⁴, Philipp Ehses⁴, and Renzo Huber^3
1Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States, ²Advanced MRI Technologies, Sebastopol, CA, United States, ³Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, ⁴German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany

Laminar-specific fMRI with CBV-sensitive VASO can address neuroscience research questions on directional information processing within and across brain areas. However, conventional 0.8mm resolutions cannot Nyquist sample the individual layer-groups of interest (e.g. Layers II/III from layer IVc in V1). Here we implement, evaluate, and apply a 0.39-0.45mm (iso.) VASO protocol on the NextGen 7T scanner to resolve layer-features that could not be resolved in humans before. We find that 0.45 mm protocols are possible if the sequence parameters of EPI-segmentation and GRAPPA acceleration are differently optimized than one would do for conventional fMRI protocols.

Renzo Huber¹, Lisa Kronbichler², Rüdiger Stirnberg³, Luca Vizioli⁴, Philipp Ehses³, Tony Stöcker³, Sara Fernández-Cabello⁵, Benedikt A Poser¹, and Martin Kronbichler^6,7
1FPN, Uni Maastricht, Maastricht, Netherlands, ²Department of Psychiatry, Psychotherapy and Psychosomatics, Christian‐Doppler Medical Centre, PMU, Salzburg, Austria, ³German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ⁴Department of Radiology, University of Minnesota, Center for Magnetic Resonance Research, Minneapolis, MN, United States, ⁵Norwegian Centre for Mental Disorders Research (NORMENT), Institute of Clinical Medicine, Uni Oslo, Oslo, Norway, ⁶Neuroscience Institute, Christian Doppler Medical Centre, PMU, Salzburg, Austria, ⁷Centre for Cognitive Neuroscience & Department of Psychology, University of Salzburg, Salzburg, Austria

Sub-millimeter functional imaging at ultra high field (UHF) strengths can capture cortical layer-specific functional information flow within and across brain systems. However, UHF scanners are only available to appr. 100 privileged imaging centers, globally. In this work, we implement, characterise and apply a CBV-sensitive VASO sequence setup for widely accessible 3T scanners. We find that the longer T2*, and shorter T1 relaxation times at 3T can account for some of the lower z-magnetization in the inversion-recovery VASO sequence compared to 7T and 9.4T. We conclude that layer-fMRI VASO is applicable without too much further ado at 3T.

Tun-Wei Hsu^1,2,3, Chia-Hung Wu^1,4,5, Hsiu-Mei Wu^1,4, Kuan-Lin Lai^4,6,7, Shih-Pin Chen^4,6,7,8, Shuu-Jiun Wang^4,6,7, Jiing-Feng Liring^1,4, and Wan-Yuo Guo^1,4
1Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, ²Integrated PET/MR Imaging Center, Taipei Veterans General Hospital, Taipei, Taiwan, ³Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming Chiao Tung University, Taipei, Taiwan, ⁴School of Medicine, College of Medicine, National Yang-Ming Chiao Tung University, Taipei, Taiwan, ⁵Institute of Clinical Medicine, National Yang-Ming Chiao Tung University, Taipei, Taiwan, ⁶Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ⁷Brain Research Center, National Yang-Ming Chiao Tung University, Taipei, Taiwan, ⁸Division of Translational Research, Taipei Veterans General Hospital, Taipei, Taiwan

Reversible cerebral vasoconstriction syndrome (RCVS) is a reversible segmental and multifocal vasoconstriction of the cerebral arteries and is believed to relate to autonomic network over-activity. We used Long Short-Term Memory networks (LSTMs), a type of deep neural network designed to handle time sequence data, to learn directly from the rs-fMRI time-series for classification of individuals with RCVS and healthy controls based on the regions in autonomic and other functional networks. These results provide methodological implications for rs-fMRI data of RCVS patients involved in the analysis and are a key element in future studies. 

Ottavia Dipasquale¹, Alexander Cohen², Daniel Martins¹, Fernando Zelaya¹, Federico Turkheimer¹, Mattia Veronese¹, Steve Williams¹, Baolian Yang³, Suchandrima Banarjee⁴, and Yang Wang^2
1Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom, ²Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, ³GE Healthcare, Waukesha, WI, United States, ⁴GE Healthcare, Menlo Park, CA, United States

This work is a proof of concept for the integration of ASL fMRI and molecular imaging using REACT, a novel analytical strategy that enriches functional data with the molecular information on the neurotransmitter distribution density. We applied REACT to high-resolution, whole-brain simultaneous ASL/BOLD data to estimate BOLD- and perfusion-weighted (PW)-based functional connectivity maps related to specific molecular systems and compared the results from the two fMRI modalities, showing very similar patterns of molecular-enriched functional connectivity. Our findings show that the PW signal is as informative as BOLD in terms of detection of functional circuits associated to specific molecular pathways. 

Stefano Moia¹, Gang Chen², Eneko Uruñuela¹, Rachael C. Stickland³, Maite Termenon¹, César Caballero-Gaudes¹, and Molly G. Bright^3,4
1Basque Center on Cognition, Brain and Language, Donostia, Spain, ²NIMH/NIH/HHS, Bethesda, MD, United States, ³Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States, ⁴Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States

Resting State Fluctuations (RSF) metrics are frequently associated with vascular and physiological factors, to the point of being suggested as alternative estimates of cerebrovascular reactivity (CVR) and as tools for fMRI data calibration. Using a densely sampled fMRI dataset, we demonstrate high individual variability in the inter-session relationships between RSF metrics and CVR. Moreover, while physiological factors such as blood pressure show a significant relationship with CVR, they do not with common RSF metrics. These results indicate that RSF parameters might not be suitable alternatives for CVR, and may not properly account for inter-individual physiological variations in BOLD fMRI data.

Tamar van Asch¹, Nathan De Jong¹, Walter Backes¹, Sebastian Köhler ², Martin van Boxtel², Miranda Schram³, and Jacobus Jansen^1
1Radiology, Maastricht University Medical Center, Maastricht, Netherlands, ²Psychiatrie & Neuropsychologie, School for Mental Health and Neuroscience, Maastricht, Netherlands, ³Internal Medicine, Maastricht University, Maastricht, Netherlands

There is a growing need for the understanding of the process of ageing and the ability to predict who is at risk of neurodegenerative diseases and mortality. This study aims to develop and train a convolutional neural network on structural brain connectivity data to predict age. dMRI is used to map the structural connectivity of the brain. The dataset comprises 3494 subjects from The Maastricht Study, a cohort study of individuals aged between 40 and 77 years. Brain age prediction on the test set resulted in a Pearson’s correlation coefficient of 0.70 and a mean absolute error of 5.1 years.

Alexander Mark Weber^1,2, Johann Drayne^1,2, Olivia Campbell^1,2, Cecil Chau^2,3, Steven Miller⁴, and Ruth Grunau^2,3
1Brain, Behaviour & Development, BC Children's Hospital Research Institute, Vancouver, BC, Canada, ²University of British Columbia, Vancouver, BC, Canada, ³BC Children's Hospital Research Institute, Vancouver, BC, Canada, ⁴Division of Neurology and Centre for Brain & Mental Health, SickKids, Toronto, ON, Canada

It has been found that fractal analysis of the BOLD signal in fMRI can be used to measure brain functioning, development, and health. There has to our knowledge, however, not been any fractal analysis fMRI studies done in newborns. By computing the mean Hurst exponent in 9 resting state networks and in a grey matter mask. We found the largest increase in the Hurst exponent between pre-term and term equivalent aged subjects was in the motor and visual network. This motivates the need of further exploration of fractal analysis as a measure of brain dynamics in pre-term infants.

Xingfeng Shao¹, Jun Hua², and Danny JJ Wang^1
1Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, ²Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States

In this study, we propose a novel pulse sequence to simultaneously acquire laminar ASL, VASO and T2-BOLD signals with high spatial resolution. Experiments were performed on the M1 to characterize concurrent layer-dependent CBF, CBV, T2 BOLD and CMRO2 signal changes to sensory input and motor output. Both positive CBF/CBV/CMRO2 and negative VASO  profiles show a clear ‘double-peak’ pattern, which is consistent with the hypothesis that FT engages neural activity of somatosensory input in the superficial layers and motor output in the deep layers. The BOLD response mainly peaked in superficial layers due to dominant contribution of pial veins.